Novel human ulip/crmp protein and use thereof in diagnosis and treatment of cancers and paraneoplastic neurological syndromes

ABSTRACT

The invention concerns a purified polypeptide, called ULIP6, comprising an amino acid sequence SEQ ID NO 2, the nucleic acid coding for said polypeptide, a non-coding sequence in 3′ of said encoding sequence and their use in diagnosis and treatment of cancers and paraneoplastic neurological syndromes.

[0001] The invention relates to a novel human ULIP/CRMP protein and tothe use thereof in diagnosis and treatment of cancers and paraneoplasticneurological syndromes.

[0002] Paraneoplastic neurological syndromes (PNSs) occur in theinstance of a cancer, often before its discovery, and are not connectedto either the tumor proliferation itself (direct invasion, metastases)or the treatment. Their frequency is estimated to be, overall,approximately 1% of cancers. Several clinical pictures have beenindividualized for a long time (encephalomyelitis, Denny-Brown sensoryneuropathy, cerebella atrophy, limbic encephalitis, opsoclonus, etc.)corresponding in fact to the either elective or preferential attack ofcertain groups of neurons. The frequency of inflammatory cells in thevicinity of the lesions for many years brought to mind the possibilityof an autoimmune or viral process. The more recent demonstration ofautoantibodies in the serum and in the cerebrospinal fluid (CSF) ofpatients suffering from PNS, specific for the type of tumor and for thetype of neurons which degenerate, has revived the hypothesis thatautoimmunity contributes to generating this pathological condition(Graus et al., 1985; Greenlee et al., 1983).

[0003] Besides the presence of a high titer of these antibodies in theblood and the CSF of patients, there are several arguments suggestingthat PNSs are the product of autoimmune mechanisms. Thus, the antigensrecognized in the central nervous system are also present in the tumorsof patients (Anderson et al., 1987). Antibodies specifically directedagainst these antigens and also B and T lymphocytes are found within thetumor tissue (Hetzel et al., 1990).

[0004] These data suggest that the autoimmune process could be triggeredby the expression of tumor antigens. A crossed immunity process couldcause the lesions in the central nervous system. Other arguments alsoindicate that the cerebral lesions result from the autoimmune response.Thus, in the brain of the patients, the specific antibody titer ishigher than that of the serum and of the CSF (Dalmau et al., 1991). Inaddition, in the case of encephalomyelitis associated with anti-Huantibodies, there is an intense lymphocytic reaction, made up of B and Tcells, located in proximity to neurons undergoing destruction (Dalmau etal., 1991; Graus et al., 1990).

[0005] Several types of autoantibody allowing precise syndromicgroupings as a function of immunological, neurological andcancer-related criteria have been described.

[0006] Thus, anti-Yo antibodies are found in the serum and the CSF ofwomen having paraneoplastic cerebella atrophy and a gynecological cancer(ovary, breast or uterus) (Greenlee et al., 1983; Jaeckle et al., 1985).

[0007] These antibodies recognize two cytoplasmic proteins, of 34 and 62kDa, specific for Purkinje cells of the cerebellum.

[0008] Anti-Ri antibodies are found in the serum and the CSF of patients(mainly women) having opsomyoclonus, a cerebella syndrome and breastcancer. These antibodies recognize two proteins, of 50 and 80 kDa,specific for central nervous system neurons (Luque et al., 1991).

[0009] Anti-Hu antibodies are most commonly encountered in the course ofPNSs. They are found in the serum and the CSF of patients havingDenny-Brown's syndrome or encephalomyeloneuritis and small-cell lungcancer (Graus et al., 1985; Dalmau et al., 1992). These autoantibodiesrecognize several proteins, of 37 to 45 kDa, expressed specifically byall the neurons of the nervous system.

[0010] Another type of autoantibody has been identified in patientshaving PNS: anti-CV2 antibodies (Antoine et al., 1993; Honnorat et al.,1996). The latter are atypical, in the sense that the antigenic targetrecognized in adulthood is essentially non-neuronal, althoughpost-mortem analysis of the brain of four patients makes it possible toobserve neuronal loss, gliosis and an inflammatory processcharacteristic of PNSs.

[0011] The originality of the discovery of these autoantibodies lies,firstly, in their demonstration. The latter had evaded all the usualinvestigations which consisted in revealing the antigens recognized, byimmunohistochemistry on post-mortem brain. The antigen recognized is infact soluble and disappears from post-mortem brain under the majority ofconditions for fixing. Only fixing of human post-mortem tissue byimmersion in paraformaldehyde, or fixing in situ by perfusion ofparaformaldehyde in animals, has made it possible to reveal the presenceof these antibodies in the CSF or the serum of patients suffering fromPNS (Antoine et al., 1993; Honnorat et al., 1996).

[0012] The anti-CV2 autoantibodies present in the sera of patientssuffering from paraneoplastic neurological syndrome (PNS) have beendefined by their ability to recognize, by indirect immunohistochemistry,a cytoplasmic antigen expressed specifically, in adult rat brain, by asubpopulation of oligodendrocytes of the brain stem, of the medulla andof the cerebellum.

[0013] The originality of these autoantibodies lies, secondly, in theirdiagnostic value. Their presence in the serum or the CSF of patients isof diagnostic value since it makes it possible to specify theparaneoplastic origin of a neurological syndrome. The discovery of theseantibodies, when it precedes that of cancer, directs the search for thiscancer and enables it to be discovered. Such was the case for sixpatients out of 19 having anti-CV2 antibodies. The clinical disorderswere different depending on the patients, some of them exhibiting apicture of limbic encephalitis, others encephalomyeloneuritis and othersLambert-Eaton syndrome. Nevertheless, in more than 60% of cases, thecerebella syndrome was predominant. The most commonly associated tumorwas small-cell lung cancer (60% of cases).

[0014] Experiments on newborn rat brains have shown that these anti-CV2antibodies react with a 66 kDa protein (Honnorat et al., 1996).

[0015] In adult brain, this antigen is located in a subpopulation ofoligodendrocytes or in cells which retain differentiation capacities inthe adult brain (olfactory bulb, dentate gyrus). The antigen recognizedis thought to play a role in neuronal survival, vianeuron/oligodendrocyte interactions, as suggested by the loss of neuronsobserved in the post-mortem brain of patients suffering from PNS.

[0016] Its very restricted expression in adulthood contrasts with verystrong and transient expression in the central and peripheral nervoussystem in development, suggesting the probable role of this antigen inthe development of the nervous system.

[0017] In application WO 98/37192 and the article by Honnorat et al.from 1999, the target antigen of the anti-CV2 autoantibodies, whichcorresponds to a protein designated “POP-66” for “paraneoplasticoligodendrocyte protein 66 kDa”, was identified as being the human formof the ULIP-4 protein. The ULIP (for “Unc-33 like phosphoprotein”)proteins are involved in the control of neuronal development and axonaltransport (Byk et al., 1996). Four members of this family had beenidentified by three different teams (Byk et al., 1998, Wang andStrittmatter, 1996; and Hamajima et al., 1996). A thorough search forpossible other members of this family had come to nothing.

[0018] The authors of the present invention were then confronted withnew results, which were not coherent with the identification establishedby application WO 98/37192; although all the anti-CV2 sera tested onHela cells unquestionably recognized the recombinant ULIP 4 protein inimmunohistochemistry, only 20% of these sera recognized the ULIP 4protein by Western blotting on these same cell extracts. Now, all theanti-CV2 sera tested recognized, moreover, by Western blotting, the same66 kDa protein after immunoprecipitation, on brain extracts. Inaddition, the ULIP4 mRNA was only very weakly expressed inoligodendrocytes by in situ hybridization. Based on these data, theauthors of the present invention supposed that a new member of the ULIPfamily, unidentified to date, strongly expressed by oligodendrocytes andrecognized in Western blotting by all the anti-CV2 sera, could exist.

[0019] The authors of the present invention have now demonstrated that,contrary to what was proposed by application WO 96/37192, POP-66, themajor target antigen of the anti-CV2 autoantibodies, is not the ULIP 4protein but another protein. They have succeeded in characterizing thisprotein. It is a novel human protein of the ULIP family, designatedULIP6.

[0020] ULIP 6 comprises, in its C-terminal portion, a major epitoperecognized by anti-CV2 antibodies in Western blotting.

[0021] A subject of the present invention is therefore a purified ULIP 6polypeptide comprising the amino acid sequence SEQ ID No. 2.

[0022] An epitopic fragment of the polypeptide mentioned above,comprising the sequence SEQ ID No. 4, is also included in the presentinvention. More particularly, a subject of the invention is the purifiedpeptide of sequence SEQ ID No. 4.

[0023] A subject of the present invention is also an isolated nucleicacid encoding the ULIP6 polypeptide as defined above, preferablycomprising the nucleotide sequence SEQ ID No. 1. The sequence SEQ ID No.1 has a 5′ noncoding region (nucleotides 1 to 162), an open readingframe (nucleotides 163 to 1854) and a 3′ noncoding region (nucleotides1855 to 3074).

[0024] A subject of the present invention is also an isolated nucleicacid comprising the nucleotide sequence SEQ ID No. 3, which correspondsto the noncoding region in 3′ of the human coding sequence SEQ ID No. 1.This noncoding sequence, as well as the 5′ noncoding portion(nucleotides 1 to 162 of SEQ ID No. 1), may in particular be used forpreparing specific probes.

[0025] The polypeptide of the present invention may be synthesized byall the methods well known to those skilled in the art. The polypeptideof the invention may, for example, be synthesized by synthetic chemistrytechniques, such as synthesis of the Merrifield type, which isadvantageous for reasons of purity, of antigenic specificity and of lackof unwanted by-products, and for its ease of production.

[0026] A recombinant ULIP6 protein can also be produced using a methodin which a vector containing a nucleic acid comprising the sequence SEQID No. 1 is transferred into a host cell, which is cultured underconditions which allow expression of the corresponding polypeptide.

[0027] The protein produced can then be recovered and purified.

[0028] The purification methods used are known to those skilled in theart. The recombinant polypeptide obtained can be purified from celllysates and extracts, and from the culture medium supernatant, usingmethods employed individually or in combination, such as fractionation,chromatography methods, immunoaffinity techniques using specific mono-or polyclonal antibodies, etc.

[0029] The nucleic acid sequence of interest, encoding the ULIP6polypeptide, may be inserted into an expression vector, in which it isfunctionally linked to elements for regulating its expression, such asin particular transcription promoters, activators and/or terminators.

[0030] The signals controlling the expression of the nucleotidesequences (promoters, activators, termination sequences, etc.) arechosen as a function of the cellular host used. To this effect, thenucleotide sequences according to the invention may be inserted intovectors which replicate autonomously in the chosen host, or vectorswhich integrate in the chosen host. Such vectors will be preparedaccording to the methods commonly used by those skilled in the art, andthe clones resulting therefrom can be introduced into a suitable hostusing standard methods, such as, for example, electroporation or calciumphosphate precipitation.

[0031] The cloning and/or expression vectors as described above,containing a nucleotide sequence defined according to the invention, arealso part of the present invention.

[0032] The invention is also directed toward the host cells transfected,transiently or stably, with these expression vectors. These cells can beobtained by introducing into host cells a nucleotide sequence insertedinto a vector as defined above, and then culturing said cells underconditions which allow replication and/or expression of the transfectednucleotide sequence.

[0033] The cellular host may be chosen from prokaryotic systems, such asbacteria, or eukaryotic systems, such as, for example, yeasts, insectcells, CHO cells (Chinese hamster ovary cells) or any other systemadvantageously available. A preferred cellular host for expressing theproteins of the invention consists of the bacterium E. coli.

[0034] The nucleotide sequences of the invention may or may not be ofartificial origin. They may be DNA or RNA sequences obtained byscreening sequence libraries using probes developed on the basis of thesequence SEQ ID No. 1 or 3. Such libraries may be prepared byconventional molecular biology techniques known to those skilled in theart.

[0035] The nucleotide sequences according to the invention may also beprepared by chemical synthesis, or else by mixed methods which includechemical or enzymatic modification of sequences obtained by screeninglibraries.

[0036] This nucleic acid makes it possible to prepare nucleotide probescapable of hybridizing strongly and specifically with a nucleic acidsequence, a genomic DNA sequence or a messenger RNA sequence, encoding apolypeptide according to the invention or a biologically active fragmentthereof. Suitable hybridization conditions correspond to the temperatureand ionic strength conditions usually used by those skilled in the art(Sambrook et al., 1989), preferably to temperature conditions of between(T_(m) minus 5° C.) and (T_(m) minus 30° C.) and even more preferably totemperature conditions of between (T_(m) minus 5° C.) and (T_(m) minus10° C.) (high stringency), Tm being the theoretical melting temperature,defined as being the temperature at which 50% of the paired strandsseparate. Such probes are also part of the invention. They may be usedas a diagnostic tool in vitro for detecting, via hybridizationexperiments, transcripts specific for the polypeptides of the inventionin biological samples, or for demonstrating aberrant syntheses orgenetic abnormalities resulting from a polymorphism, from mutations orfrom incorrect splicing.

[0037] The probes of the invention comprise a minimum of 10 nucleotides,and as a maximum comprise all of a nucleotide sequence SEQ ID No. 1 or3, or of the strand complementary thereto.

[0038] The nucleic acid of the invention may also be used to prepareoligonucleotide primers which hybridize, under high stringencyconditions, to the sequence SEQ ID No. 1 or 3.

[0039] These sense and/or antisense oligonucleotide primers may be ofuse for sequencing reactions or specific amplification reactionsaccording to the “PCR” (polymerization chain reaction) technique or anyother variant thereof.

[0040] Preferentially, the probes or primers of the invention arelabeled prior to their use. For this, several techniques are within thescope of those skilled in the art, such as, for example, fluorescent,radioactive, chemiluminescent or enzymatic labeling.

[0041] The methods for diagnosis in vitro in which these nucleotideprobes are used for detecting aberrant syntheses or geneticabnormalities, such as loss of heterozygosity and genetic rearrangement,in the nucleic acid sequences encoding a ULIP6 polypeptide according tothe invention, are included in the present invention. Such a type ofmethod comprises:

[0042] contacting a nucleotide probe of the invention with a biologicalsample under conditions which allow the formation of a hybridizationcomplex between said probe and the abovementioned nucleotide sequence,optionally after a prior step of amplification of the abovementionednucleotide sequence;

[0043] detecting the hybridization complex possibly formed;

[0044] optionally sequencing the nucleotide sequence which forms thehybridization complex with the probe of the invention.

[0045] The probes of the invention can also advantageously be used fordetecting chromosomal abnormalities.

[0046] The nucleotide sequences according to the invention are,moreover, useful in the therapeutic field, for preparing antisensesequences capable of hybridizing specifically with a nucleic acidsequence, including a messenger RNA, which can be used in gene therapy.A subject of the invention is thus antisense sequences capable ofinhibiting, at least partially, the production of a polypeptideaccording to the invention, as defined above.

[0047] They are of more particular use in the treatment of disorders ofthe central and peripheral nervous system and of vision, in particularin the treatment of paraneoplastic neurological syndromes, and also inanticancer treatment, in particular for tumors associated withparaneoplastic neurological syndromes.

[0048] The exploitation of the ULIP proteins, and in particular ULIP6,and also of the antibodies directed against these proteins, is promisingin various fields.

[0049] Thus, detection of the anti-CV2 autoantibody byimmunofluorescence on fixed animal brain is currently used as adiagnostic test.

[0050] The production of recombinant ULIP6 protein according to theinvention makes it possible to produce a rapid and reliable test (of theElisa or Western blotting type) for detecting anti-CV2 antibodies.

[0051] Such tests already exist for anti-Hu, anti-Yo and anti-Riantibodies. The test for detecting anti-CV2s in the serum of patientscould be prescribed in the case of suspicion of paraneoplasticneurological syndrome and would, consequently, include anti-CV2antibodies as well as the other antibodies identified in PNSs asmentioned above.

[0052] The invention is therefore also directed toward a method for thediagnosis of paraneoplastic neurological syndromes and/or for the earlydiagnosis of the formation of tumors of cancerous origin, whereinantibodies directed against a ULIP6 protein are demonstrated in abiological sample (such as blood, serum, CSF, etc.) taken from anindividual, by

[0053] contacting a biological sample taken from an individual with apurified ULIP6 polypeptide optionally attached to a support, underconditions which allow the formation of specific immunocomplexes betweensaid polypeptide and the autoantibodies possibly present in thebiological sample, and

[0054] detecting the specific immunocomplexes possibly formed.

[0055] A subject of the invention is therefore a composition useful forthe diagnosis of paraneoplastic neurological syndromes and/or for theearly diagnosis of the formation of tumors, that comprises a ULIP6polypeptide or an epitopic fragment of said polypeptide.

[0056] Advantageously, instead of the complete polypeptide, theC-terminal portion comprising the dominant epitope (for example thefragment ranging from amino acid No. 475 to amino acid 564) may be used.An epitopic fragment of the ULIP 6 polypeptide, comprising the sequenceSEQ ID No. 4, may in particular be used. The peptide of sequence SEQ IDNo. 4 has thus made it possible to produce antibodies which are veryspecific for ULIP6.

[0057] A subject of the invention is also a kit for the diagnosis ofparaneoplastic neurological syndromes and for the early diagnosis of theformation of tumors, using a biological specimen, comprising:

[0058] at least one purified ULIP6 polypeptide, optionally attached to asupport,

[0059] means for revealing the formation of specific antigen/antibodycomplexes between an anti-ULIP6 autoantibody and said purified ULIP6polypeptide, or polypeptide derivative or fragment, and/or means forquantifying these complexes.

[0060] A subject of the invention is also the mono- or polyclonalantibodies or fragments, chimeric antibodies or immunoconjugatesthereof, obtained using a purified ULIP polypeptide or peptidecomprising an amino acid sequence SEQ ID No. 2 or No. 4, and usethereof, for purifying or detecting a ULIP protein in a biologicalsample.

[0061] Polyclonal antibodies may be obtained from the serum of an animalimmunized against the protein, produced, for example, by geneticrecombination following the method described above, according to usualprocedures.

[0062] The monoclonal antibodies may be obtained according to theconventional method of culturing hybridomas described by Köhler andMilstein.

[0063] The antibodies may be chimeric antibodies, humanized antibodies,and Fab and F(ab′)2 fragments. They may also be in the form ofimmunoconjugates or of labeled antibodies.

[0064] The invention also relates to the use of antibodies directedagainst the ULIP6 protein, for demonstrating a ULIP6 protein inneoplasms and paraneoplastic neurological syndromes, for diagnosticpurposes.

[0065] Preferentially, the invention relates to the use of monoclonalantibodies obtained from the polyclonal anti-CV2 serum of patients byimmortalization of lymphocytes, according to the usual techniques knownto those skilled in the art.

[0066] Thus, the antibodies directed against a protein of the ULIPfamily are of use for detecting abnormal expression of ULIP protein inpatients having neurological syndromes, in whom no cancer has beendiagnosed using conventional methods. This abnormal expression of ULIP6protein may be correlated with the existence of a cancer which had notbeen detected. Thus, the antibodies directed against the ULIP6 proteinare of use for the early diagnosis of a cancer.

[0067] Human or nonhuman antibodies, obtained from patients or obtainedafter immunization with all or part of the ULIP6 protein, as definedabove, may also be labeled in a detectable manner, for example byassociation with a radioactive element, and may be injected into anindividual. Using imaging processes well known to those skilled in theart, they may make it possible to detect or diagnose a cancerous tumorafter antigenic reaction of these antibodies with the cells of thetumor.

[0068] A subject of the invention is therefore also a method fordetecting or diagnosing a cancerous tumor, comprising the administrationto a patient of an antibody as defined above, labeled in a detectablemanner, and the visualization by imaging of the site of attachment ofthis antibody.

[0069] A subject of the invention is also a pharmaceutical compositioncomprising at least one therapeutic agent chosen from a purified ULIP6protein, or a nucleic acid encoding said protein, an antisense sequencecapable of hybridizing specifically with a nucleotide sequence SEQ IDNo. 1 or No. 3, or an antibody directed against said protein, combinedwith a pharmaceutically acceptable vehicle.

[0070] The invention preferentially comprises pharmaceuticalcompositions comprising, as active principle, a purified ULIP6polypeptide, preferentially in soluble form, combined with apharmaceutically acceptable vehicle.

[0071] Such compositions offer a novel approach for treating disordersof the central and peripheral nervous system and of vision, and inparticular paraneoplastic neurological syndromes. Moreover, they are ofuse for treating neurological disorders linked to neuronal loss and/orunderexpression of the ULIP6 protein in the nervous system.

[0072] Thus, ULIP6 also proves to be of value in neurodegenerativepathological conditions, such as multisystemic atrophies which aredisorders similar to those of PNSs and for which an abnormality of anoligodendrocytic subpopulation has been detected (Papp et al., 1992).

[0073] The compositions according to the invention are, moreover, of usein anticancer treatment.

[0074] The antibodies directed against the ULIP6 protein may be combinedwith antineoplastic agents, thus allowing targeting of the medicinalproducts to the tumor cells.

[0075] They may also be combined with a hydrophilic chemical groupchosen so as to cross or so as not to cross the blood-brain barrier,depending on the type of tumor.

[0076] The ULIP6 protein and also the nucleotide sequences describedabove, and the antisense sequences or oligonucleotides, may be of use inthe treatment of any type of cancer in which a gene encoding the ULIP6protein is involved. Among examples of cancers, mention may be made ofperipheral tumors, such as small-cell lung cancer, thymoma, breastcancer and ovarian cancer, and also brain tumors, preferably primarybrain tumors of glial origin. The expression of ULIP6 in thenonproliferative cells of normal brain, its absence in normal tissues,such as lung or thymus, for example, its differential reexpressionduring tumorigenesis in these tissues, and the modulation of itsexpression in a tumor line during differentiation suggest, in thisregard, that ULIP 6 may be a tumor suppressor gene.

[0077] A compound or a mixture of compounds of synthetic or naturalorigin, which inhibits the action of ULIP 6, may also be used.

[0078] Alternatively, stimulation of ULIP 6 may be desired. A compoundor a mixture of compounds of synthetic or natural origin which activatesthe expression or the action of the ULIP 6 protein may then be used.

[0079] These activating or inhibiting compounds may be included inpharmaceutical compositions.

[0080] Preferentially, the pharmaceutical compositions according to theinvention may be administered systemically, preferably intravenously,intramuscularly, intradermally or orally.

[0081] Their optimal methods of administration, dosages andpharmaceutical forms may be determined according to the criteriagenerally taken into account in establishing a therapeutic treatmentsuitable for a patient, such as, for example, the age or bodyweight ofthe patient, the seriousness of his or her general condition, thetolerance to the treatment and the side effects observed, etc.

[0082] The invention also comprises the use of a purified ULIP6 protein,a nucleic acid encoding said protein or belonging to the noncodingregions of the ULIP6 gene, an antisense sequence capable of hybridizingspecifically with a nucleotide sequence SEQ ID No. 1 or No. 3, or anantibody directed against said protein, combined with a pharmaceuticallyacceptable vehicle, for manufacturing a medicament intended to treatneurodegenerative diseases and neoplasms.

[0083] Finally, a subject of the invention is a method for treatingneurodegenerative diseases and neoplasms, comprising the administrationof a therapeutically effective amount of a pharmaceutical composition asdefined above to an individual requiring such a treatment.

[0084] The examples and figures, for which the legends are presentedbelow, are given by way of illustration.

LEGENDS TO THE FIGURES

[0085]FIG. 1 represents a Western blot performed on protein extracts ofE. coli expressing the fusion protein GST-ULIP6 C-term. These extractswere separated by SDS-12.5% PAGE, transferred onto a PVDF membrane andincubated with human sera. Lanes 1 to 14: anti-CV2 sera; lanes 15 to 17:control sera.

[0086]FIG. 2 represents a Western blot performed on GST-ULIP6 C-termfusion proteins after purification on agarose-glutathione beads. Theprotein is recognized by two anti-CV2 sera (lane 1: serum 94-822, lane2: serum 95-590) but not by a control serum (lane 3).

EXAMPLE 1 Identification of the Target for Anti-CV2 Antibodies

[0087] After expression of the recombinant proteins of the Ulip familyin HeLa cells, the authors of the invention were able to show that theanti-CV2 sera then in their possession all recognized Ulip4 byimmunohistochemistry. This result would suggest that Ulip4 could be themajor antigen recognized by the anti-CV2 sera (Honnorat et al., 1999).On the other hand, when a larger group of sera was tested by Westernblotting on the Ulip4 protein expressed in E. coli, they noticed thatwhile several anti-CV2 sera unquestionably recognized the recombinantUlip4 protein, some did not recognize it, although all the anti-CV2 serarecognized, by Western blotting, the same 66 kDa protein afterimmunoprecipitation of protein extracts from brains (Honnorat et al.,1996). In addition, by in situ hybridization, the oligodendrocytes didnot express the Ulip4 messenger RNA. The authors of the invention thenput forward the hypothesis of the existence of another proteinhomologous to the Ulip proteins, which had not yet been described, andwhich was expressed by oligodendrocytes.

[0088] In order to search for this protein, an anti-CV2 serum, which didnot recognize recombinant Ulip4 by Western blotting, was used to screenan expression library. A cDNA library of human spinal cord, the site ofmaximum expression of the CV2 antigen in adults, cloned into the lambdagt11 phage was chosen (Clontech, Palo Alto, U.S.A.). The phages werescreened at a density of 2×10⁴ pfu per 150 mm-diameter dish. Afterincubation for 3 hours 30 minutes at 42° C., the dishes were coveredwith a nitrocellulose membrane incubated in IPTG (10 mM), andreincubated for 3 hours at 37° C. The membranes were then saturated inPBS-Tween-skimmed milk, and then incubated overnight with the serumdiluted to {fraction (1/100)}. The membranes were then washed inPBS-Tween and then incubated with a peroxidase-labeled anti-humanimmunoglobulin antiserum. After washing, the membranes were revealed bythe diaminobenzidine method. The clones giving a positive signal werepurified by successive subculturing until 100% of positive clones wasobtained. Four cDNAs of 1400 to 1700 base pairs and encoding theC-terminal portion of the same protein were identified. The clone havingthe largest coding sequence (clone 97) contained 1490 base pairs(nucleotides 1585 to 3074 of sequence ID No. 1) with an open readingframe of 270 nucleotides encoding a 90 amino acid polypeptide (aminoacids 475 to 564 of sequence ID No. 2). After a homology search indatabanks, it was noted that this polypeptide (named in the remainder ofthe study Ulip6 C-Term) exhibited a homology of 35% with the C-terminalportion of each of the already known members of the Ulip family, andthat no homology existed with other protein families.

EXAMPLE 2 Production of the Recombinant Protein GST-ULIP6 C-Term

[0089] To confirm that this polypeptide was indeed the antigenrecognized by the anti-CV2 sera, the coding phase of clone 97 was clonedinto a bacterial expression vector, pGex 2T (Pharmacia Amersham Biotech,Sweden). This vector allows expression, in E. coli, of the protein ofinterest as a fusion with glutathione-S-transferase (GST, 26 kDa). ByWestern blotting, 16 of the 18 anti-CV2 sera tested recognized theGST-Ulip6-CTerm fusion protein in a bacterial protein extract, i.e. 89%positives (FIG. 1). It should be noted that the Ulip6 C-Term polypeptidehas a molecular weight of 10 kDa, which represents approximately 15% ofa 66 kDa protein. None of these sera recognized GST alone. 100 controlsera were also tested. None showed any reactivity with respect to theGST-Ulip6 C-Term fusion protein. With the aim of having as specific atest as possible, the authors of the invention also tested the anti-CV2sera on the GST-Ulip6 C-Term fusion protein purified onagarose-glutathione beads. FIG. 2 shows an example of the resultsobtained by Western blotting.

EXAMPLE 3 Northern Blotting on Human Spinal Cord RNA

[0090] To determine the size of the transcript of the Ulip6 gene, aNorthern blotting analysis was carried out on purified polyA+ RNAsextracted from human spinal cord (Clontech, Palo Alto, U.S.A.). Theprobe corresponded to the entire clone 97 labeled with alpha ³²p dCTP.The RNAs were separated on a 1.2% agarose formaldehyde electrophoresisgel and transferred onto a nylon membrane. After prehybridization withthe rapid hybridization solution (Clontech, Palo Alto, U.S.A.), themembrane was incubated with the probe for one hour. After washing, themembrane was exposed on a film overnight at −80° C. A single bandcorresponding to a 5 kb transcript was revealed.

EXAMPLE 4 In Situ Hybridization on Spinal Cord

[0091] To verify the presence of the Ulip6 messenger RNA inoligodendrocytes, an in situ hybridization analysis was carried out onfrontal sections of medulla. The probe used was a cold RNA probeobtained by transcription of clone 97 subcloned into pBluescript SK(Stratagene) and labeled with digoxigenin. A sense probe was used asnegative control. Specific labeling of oligodendrocytes could beobserved.

EXAMPLE 5 Production of a Rabbit Anti-Ulip6 Antibody

[0092] Polyclonal antibodies were produced by immunizing rabbits againsta peptide specific to the Ulip6 protein (peptide PepUlip6=“KEMGTPLADTPTRPVTRHGG” of sequence SEQ ID No. 4, corresponding toamino acid fragment 505 to 524 on SEQ ID No. 2). The peptide wassynthesized on a peptide synthesizer (432A Peptide Synthesizer SYNERGY,Applied Biosystems), by the company COVALAB (Lyon, France). The purityof the samples was controlled by HPLC and mass spectrometry. Onemilligram of peptide coupled to hemocyanine and with complete Freund'sadjuvant was injected into rabbits (COVALAB, Lyon, France) . Every 3weeks, a further injection of 0.5 mg was given. The production ofantibodies and their specificity were analyzed by Western blotting andimmunohistochemistry, using preimmune sera as a control.

[0093] The antibodies obtained recognized the GST-Ulip6 C-Term proteinby Western blotting, a 66 kDa protein on brain extracts, andspecifically labeled oligodendrocytes by immunohistochemistry on ratmedulla sections.

EXAMPLE 6 Search for the Complete Ulip6 Sequence

[0094] In order to obtain a complete Ulip6 cDNA, the human spinal cordcDNA library, cloned into the lambda gt11 phage (Clontech, Palo Alto,U.S.A.), was screened with a radioactive probe. This probe, obtained byPCR, was labeled with alpha ³²p dCTP, and corresponded to nucleotides1585 to 1854 of the sequence ID No. 1. The phages were screened at adensity of 2×10⁴ pfu per 150 mm-diameter dish. After incubation for 6hours at 37° C., a replica was obtained on a nylon membrane. Thismembrane was treated so as to denature the phages, and the DNA was thenfixed overnight at 42° C. After prehybridization with the rapidhybridization solution (Clontech, Palo Alto, U.S.A.), the membrane wasincubated for one hour with the radioactive probe. After washing, themembrane was exposed on a film overnight at −80° C. Clones giving apositive signal were purified by successive subculturing until 100% ofpositive clones was obtained. The largest cDNA obtained comprised 3074nucleotides (SEQ ID No. 1) and comprised an open reading frame of 1692nucleotides (nucleotides No. 163 to 1854 of SEQ ID No. 1). It encoded a564 amino acid protein (SEQ ID No. 2), the C-terminal portion of whichwas strictly identical to the ULIP6 C-term polypeptide (amino acids 475to 564 on SEQ ID No. 2). After alignment of the protein obtained withthe four known human ULIP/CRMP proteins, 50% homology was observed.

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[0107] Levy N., Mattei M. G., 1995, Geneprobs II, a practical approach,B. D. Hames and S. J. Higgins, Oxford University Press, pp 211-243

[0108] Luque et al., Ann. Neurol., 1991, vol. 29, pp 241-51

[0109] Sambrook et al., Molecular Cloning, a laboratory manual, 1989,9.47-9.62

[0110] Wang L. H. and Strittmatter S. M., (1996). J. Neurosci.,16:6197-6207.

1 4 1 3074 DNA Homo sapiens CDS (163)..(1854) 1 cccgccccac tctggactcccgcgctgggc gcgctgaggc ggcccccgag cgagcgcgcg 60 tgcagccgcc gccgccccgagcacccgcag ctccggcgcc gcggcgagac ggagacggac 120 cgagccacgg gcccccgcggccgcagcatc tcggaggaga ac atg ctt gcc aac 174 Met Leu Ala Asn 1 tca gccagc gtg agg atc ctc atc aag gga ggc aag gtg gtg aac gat 222 Ser Ala SerVal Arg Ile Leu Ile Lys Gly Gly Lys Val Val Asn Asp 5 10 15 20 gac tgcacc cac gag gct gac gtc tac atc gag aat ggc atc atc cag 270 Asp Cys ThrHis Glu Ala Asp Val Tyr Ile Glu Asn Gly Ile Ile Gln 25 30 35 cag gtg ggccgc gag ctc atg atc cct ggc ggg gcc aag gtg att gat 318 Gln Val Gly ArgGlu Leu Met Ile Pro Gly Gly Ala Lys Val Ile Asp 40 45 50 gcc aca gga aaactg gtg atc cct ggt ggc atc gac acc agc acc cac 366 Ala Thr Gly Lys LeuVal Ile Pro Gly Gly Ile Asp Thr Ser Thr His 55 60 65 ttc cac cag acc ttcatg aat gcc acg tgc gtg gac gac ttc tac cat 414 Phe His Gln Thr Phe MetAsn Ala Thr Cys Val Asp Asp Phe Tyr His 70 75 80 ggg acc aag gca gca ctcgtc gga ggc acc acc atg atc atc ggc cac 462 Gly Thr Lys Ala Ala Leu ValGly Gly Thr Thr Met Ile Ile Gly His 85 90 95 100 gtc ctg ccc gac aag gagacc tcc ctt gtg gac gct tat gag aag tgc 510 Val Leu Pro Asp Lys Glu ThrSer Leu Val Asp Ala Tyr Glu Lys Cys 105 110 115 cga ggt ctg gcc gac cccaag gtc tgc tgt gat tac gcc ctc cac gtg 558 Arg Gly Leu Ala Asp Pro LysVal Cys Cys Asp Tyr Ala Leu His Val 120 125 130 ggg atc acc tgg tgg gcaccc aag gtg aaa gca gaa atg gag aca ctg 606 Gly Ile Thr Trp Trp Ala ProLys Val Lys Ala Glu Met Glu Thr Leu 135 140 145 gtg agg gag aag ggt gtcaac tcg ttc cag atg ttc atg acc tac aag 654 Val Arg Glu Lys Gly Val AsnSer Phe Gln Met Phe Met Thr Tyr Lys 150 155 160 gac ctg tac atg ctt cgagac agt gag ctg tac caa gtg ttg cac gct 702 Asp Leu Tyr Met Leu Arg AspSer Glu Leu Tyr Gln Val Leu His Ala 165 170 175 180 tgc aag gac att ggggca atc gcc cgc gtc cat gct gaa aat ggg gag 750 Cys Lys Asp Ile Gly AlaIle Ala Arg Val His Ala Glu Asn Gly Glu 185 190 195 ctt gtg gcc gag ggtgct aag gag gca ctg gat ttg ggg atc aca ggc 798 Leu Val Ala Glu Gly AlaLys Glu Ala Leu Asp Leu Gly Ile Thr Gly 200 205 210 cca gaa gga atc gagatc agc cgt cca gag gag ctg gaa gct gaa gcc 846 Pro Glu Gly Ile Glu IleSer Arg Pro Glu Glu Leu Glu Ala Glu Ala 215 220 225 act cat cgt gtt atcacc att gca aac agg act cac tgt cca atc tac 894 Thr His Arg Val Ile ThrIle Ala Asn Arg Thr His Cys Pro Ile Tyr 230 235 240 ctg gtc aac gtg tccagt atc tcg gct ggt gac gtt atc gca gct gct 942 Leu Val Asn Val Ser SerIle Ser Ala Gly Asp Val Ile Ala Ala Ala 245 250 255 260 aag atg caa gggaag gtt gtg ctg gcg gag acc acc act gca cat gcc 990 Lys Met Gln Gly LysVal Val Leu Ala Glu Thr Thr Thr Ala His Ala 265 270 275 acg ctg aca ggctta cac tac tac cac cag gac tgg tcc cac gcg gct 1038 Thr Leu Thr Gly LeuHis Tyr Tyr His Gln Asp Trp Ser His Ala Ala 280 285 290 gcc tat gtc acggtg cct ccc ctg aga ctg gac acc aac acc tca acc 1086 Ala Tyr Val Thr ValPro Pro Leu Arg Leu Asp Thr Asn Thr Ser Thr 295 300 305 tac ctc atg agcctg ctg gcc aat gac act ctg aac atc gtg gca tca 1134 Tyr Leu Met Ser LeuLeu Ala Asn Asp Thr Leu Asn Ile Val Ala Ser 310 315 320 gat cac cgg cctttc acc aca aag cag aaa gct atg ggc aag gaa gac 1182 Asp His Arg Pro PheThr Thr Lys Gln Lys Ala Met Gly Lys Glu Asp 325 330 335 340 ttc acc aagatc cca cat gga gtg agt ggc gtg cag gac cgc atg agc 1230 Phe Thr Lys IlePro His Gly Val Ser Gly Val Gln Asp Arg Met Ser 345 350 355 gtc atc tgggag aga gga gtg gtt gga gga aag atg gat gag aac cgt 1278 Val Ile Trp GluArg Gly Val Val Gly Gly Lys Met Asp Glu Asn Arg 360 365 370 ttt gtg gccgtt acc agt tcc aac gca gct aag ctt ctg aac ctg tat 1326 Phe Val Ala ValThr Ser Ser Asn Ala Ala Lys Leu Leu Asn Leu Tyr 375 380 385 ccc cgc aagggc cgc att att ccc gga gcc gat gct gat gtg gtg gtg 1374 Pro Arg Lys GlyArg Ile Ile Pro Gly Ala Asp Ala Asp Val Val Val 390 395 400 tgg gac ccagaa gcc aca aag acc atc tca gcc agc acg cag gtc cag 1422 Trp Asp Pro GluAla Thr Lys Thr Ile Ser Ala Ser Thr Gln Val Gln 405 410 415 420 gga ggagac ttc aac ctg tat gag aac atg cgc tgc cac ggc gtg cca 1470 Gly Gly AspPhe Asn Leu Tyr Glu Asn Met Arg Cys His Gly Val Pro 425 430 435 ctg gtcacc atc agc cgg ggg cgc gtc gtg tat gag aac ggc gtc ttc 1518 Leu Val ThrIle Ser Arg Gly Arg Val Val Tyr Glu Asn Gly Val Phe 440 445 450 atg tgcgcc gag ggc acc ggc aag ttc tgt ccc ctg agg tcc ttc cca 1566 Met Cys AlaGlu Gly Thr Gly Lys Phe Cys Pro Leu Arg Ser Phe Pro 455 460 465 gac actgtc tac aag aag ctg gtc cag aga gag aag act tta aag gtt 1614 Asp Thr ValTyr Lys Lys Leu Val Gln Arg Glu Lys Thr Leu Lys Val 470 475 480 aga ggagtg gac cgc act ccc tac ctg ggg gat gtc gct gtt gtc gtg 1662 Arg Gly ValAsp Arg Thr Pro Tyr Leu Gly Asp Val Ala Val Val Val 485 490 495 500 caccct ggg aaa aaa gag atg gga acc cca ctc gca gac act cct acc 1710 His ProGly Lys Lys Glu Met Gly Thr Pro Leu Ala Asp Thr Pro Thr 505 510 515 cggccc gtc acc cgg cat ggg ggc atg agg gac ctt cac gaa tcc agc 1758 Arg ProVal Thr Arg His Gly Gly Met Arg Asp Leu His Glu Ser Ser 520 525 530 ttcagc ctc tct ggc tct cag atc gat gac cat gtt cca aag cga gct 1806 Phe SerLeu Ser Gly Ser Gln Ile Asp Asp His Val Pro Lys Arg Ala 535 540 545 tcagct cgg atc ctc gct cct ccc gga ggc agg tcg agt ggc att tgg 1854 Ser AlaArg Ile Leu Ala Pro Pro Gly Gly Arg Ser Ser Gly Ile Trp 550 555 560taaaggcatt gccaagcccc ccgagtgagg acgcaccgcc gccaccagcc cgcaactctc 1914cagccgaagc tgcaggggca ggagaggctg ggctgggtgg cacaccaccc gaggggggcc 1974ccgggaccca cggagccctc cctatgtctg caaagtgatt cactgtgctt cgagccaact 2034ctaacaggca ctttgagatg tgttcctcct gctgtagtcc tttctgcctt ggcctcggcg 2094ggcttttctg gggcccagga agcccacact atgcacagag cccaatgcat agagccctgg 2154ccagcccttc ctctcactcc tgcctccgct ggctttggga aagcccagac tttagtgccc 2214tgccccctgg ctgactggcc agttgcccag agcactttag cagatgtggt ttcaaagtaa 2274aggcctcctc ccccacccct taggccccgt ggtgacattt cccaagtcag acagatgtca 2334gcttcccagc catgcccagg acgtcctatc tcccccaacc cacctctggc cctgtgtagg 2394ggcagggatg ggggtggctg ggactcctgg tgcccctcgc cagcttctcc tgcgccccgc 2454ccacaccctc gggggggtca caggcccaga agggtagctg ggcggggctc gaggctggtg 2514ccaggcgcgt gtaaatggtt ttgttttgca cgtttggttt gcgcagtagt ttggtttgac 2574ttgtttgtgc atcctgtgaa aaataacggt gcttgtgtca ctagcataga atagcgacag 2634gaatagatgt ggtccttagg agacgctgca cttgacacca accagacagc acagggcagg 2694ggtggtggag ggggctgggc tcacaggcct ctcttttccc cgcctgcagt cttctgggct 2754gcgggaggcc ctggcccttt ccccttcccc tcccctcctt gtctagtttc ccacattcca 2814aaagggggcc tgggatgcta gccccagaga tgccagccct tcaggaagca ggtgtccttt 2874cccctctctg cccctgatca ctcccagcac tccccttgcc ttcccctgtc ttcacctgcc 2934accacacaca cacacacaca cacacacaca cacacacgca tggcttccta taacttcttc 2994ctgctggaca gagactcagc gctcctcctg tgtgactggc aagaggcctc atgcctgctg 3054agagagggtc gacgcggccg 3074 2 564 PRT Homo sapiens 2 Met Leu Ala Asn SerAla Ser Val Arg Ile Leu Ile Lys Gly Gly Lys 1 5 10 15 Val Val Asn AspAsp Cys Thr His Glu Ala Asp Val Tyr Ile Glu Asn 20 25 30 Gly Ile Ile GlnGln Val Gly Arg Glu Leu Met Ile Pro Gly Gly Ala 35 40 45 Lys Val Ile AspAla Thr Gly Lys Leu Val Ile Pro Gly Gly Ile Asp 50 55 60 Thr Ser Thr HisPhe His Gln Thr Phe Met Asn Ala Thr Cys Val Asp 65 70 75 80 Asp Phe TyrHis Gly Thr Lys Ala Ala Leu Val Gly Gly Thr Thr Met 85 90 95 Ile Ile GlyHis Val Leu Pro Asp Lys Glu Thr Ser Leu Val Asp Ala 100 105 110 Tyr GluLys Cys Arg Gly Leu Ala Asp Pro Lys Val Cys Cys Asp Tyr 115 120 125 AlaLeu His Val Gly Ile Thr Trp Trp Ala Pro Lys Val Lys Ala Glu 130 135 140Met Glu Thr Leu Val Arg Glu Lys Gly Val Asn Ser Phe Gln Met Phe 145 150155 160 Met Thr Tyr Lys Asp Leu Tyr Met Leu Arg Asp Ser Glu Leu Tyr Gln165 170 175 Val Leu His Ala Cys Lys Asp Ile Gly Ala Ile Ala Arg Val HisAla 180 185 190 Glu Asn Gly Glu Leu Val Ala Glu Gly Ala Lys Glu Ala LeuAsp Leu 195 200 205 Gly Ile Thr Gly Pro Glu Gly Ile Glu Ile Ser Arg ProGlu Glu Leu 210 215 220 Glu Ala Glu Ala Thr His Arg Val Ile Thr Ile AlaAsn Arg Thr His 225 230 235 240 Cys Pro Ile Tyr Leu Val Asn Val Ser SerIle Ser Ala Gly Asp Val 245 250 255 Ile Ala Ala Ala Lys Met Gln Gly LysVal Val Leu Ala Glu Thr Thr 260 265 270 Thr Ala His Ala Thr Leu Thr GlyLeu His Tyr Tyr His Gln Asp Trp 275 280 285 Ser His Ala Ala Ala Tyr ValThr Val Pro Pro Leu Arg Leu Asp Thr 290 295 300 Asn Thr Ser Thr Tyr LeuMet Ser Leu Leu Ala Asn Asp Thr Leu Asn 305 310 315 320 Ile Val Ala SerAsp His Arg Pro Phe Thr Thr Lys Gln Lys Ala Met 325 330 335 Gly Lys GluAsp Phe Thr Lys Ile Pro His Gly Val Ser Gly Val Gln 340 345 350 Asp ArgMet Ser Val Ile Trp Glu Arg Gly Val Val Gly Gly Lys Met 355 360 365 AspGlu Asn Arg Phe Val Ala Val Thr Ser Ser Asn Ala Ala Lys Leu 370 375 380Leu Asn Leu Tyr Pro Arg Lys Gly Arg Ile Ile Pro Gly Ala Asp Ala 385 390395 400 Asp Val Val Val Trp Asp Pro Glu Ala Thr Lys Thr Ile Ser Ala Ser405 410 415 Thr Gln Val Gln Gly Gly Asp Phe Asn Leu Tyr Glu Asn Met ArgCys 420 425 430 His Gly Val Pro Leu Val Thr Ile Ser Arg Gly Arg Val ValTyr Glu 435 440 445 Asn Gly Val Phe Met Cys Ala Glu Gly Thr Gly Lys PheCys Pro Leu 450 455 460 Arg Ser Phe Pro Asp Thr Val Tyr Lys Lys Leu ValGln Arg Glu Lys 465 470 475 480 Thr Leu Lys Val Arg Gly Val Asp Arg ThrPro Tyr Leu Gly Asp Val 485 490 495 Ala Val Val Val His Pro Gly Lys LysGlu Met Gly Thr Pro Leu Ala 500 505 510 Asp Thr Pro Thr Arg Pro Val ThrArg His Gly Gly Met Arg Asp Leu 515 520 525 His Glu Ser Ser Phe Ser LeuSer Gly Ser Gln Ile Asp Asp His Val 530 535 540 Pro Lys Arg Ala Ser AlaArg Ile Leu Ala Pro Pro Gly Gly Arg Ser 545 550 555 560 Ser Gly Ile Trp3 1218 DNA Homo sapiens 3 aggcattgcc aagccccccg agtgaggacg caccgccgccaccagcccgc aactctccag 60 ccgaagctgc aggggcagga gaggctgggc tgggtggcacaccacccgag gggggccccg 120 ggacccacgg agccctccct atgtctgcaa agtgattcactgtgcttcga gccaactcta 180 acaggcactt tgagatgtgt tcctcctgct gtagtcctttctgccttggc ctcggcgggc 240 ttttctgggg cccaggaagc ccacactatg cacagagcccaatgcataga gccctggcca 300 gcccttcctc tcactcctgc ctccgctggc tttgggaaagcccagacttt agtgccctgc 360 cccctggctg actggccagt tgcccagagc actttagcagatgtggtttc aaagtaaagg 420 cctcctcccc caccccttag gccccgtggt gacatttcccaagtcagaca gatgtcagct 480 tcccagccat gcccaggacg tcctatctcc cccaacccacctctggccct gtgtaggggc 540 agggatgggg gtggctggga ctcctggtgc ccctcgccagcttctcctgc gccccgccca 600 caccctcggg ggggtcacag gcccagaagg gtagctgggcggggctcgag gctggtgcca 660 ggcgcgtgta aatggttttg ttttgcacgt ttggtttgcgcagtagtttg gtttgacttg 720 tttgtgcatc ctgtgaaaaa taacggtgct tgtgtcactagcatagaata gcgacaggaa 780 tagatgtggt ccttaggaga cgctgcactt gacaccaaccagacagcaca gggcaggggt 840 ggtggagggg gctgggctca caggcctctc ttttccccgcctgcagtctt ctgggctgcg 900 ggaggccctg gccctttccc cttcccctcc cctccttgtctagtttccca cattccaaaa 960 gggggcctgg gatgctagcc ccagagatgc cagcccttcaggaagcaggt gtcctttccc 1020 ctctctgccc ctgatcactc ccagcactcc ccttgccttcccctgtcttc acctgccacc 1080 acacacacac acacacacac acacacacac acacgcatggcttcctataa cttcttcctg 1140 ctggacagag actcagcgct cctcctgtgt gactggcaagaggcctcatg cctgctgaga 1200 gagggtcgac gcggccgc 1218 4 20 PRT Homosapiens 4 Lys Glu Met Gly Thr Pro Leu Ala Asp Thr Pro Thr Arg Pro ValThr 1 5 10 15 Arg His Gly Gly 20

1. A purified polypeptide, designated ULIP6, comprising the amino acidsequence SEQ ID No. 2 or an epitopic fragment of said polypeptide,comprising the sequence SEQ ID No.
 4. 2. An isolated nucleic acidcomprising a nucleotide sequence encoding a polypeptide or an epitopicfragment of said polypeptide as defined in claim
 1. 3. The nucleic acidas claimed in claim 2, comprising a nucleotide sequence SEQ ID No.
 1. 4.An isolated nucleic acid consisting of a nucleotide sequence SEQ ID No.3 or the sequence ranging from nucleotide 1 to nucleotide 162 of SEQ IDNo.
 1. 5. A cloning and/or expression vector containing a nucleic acidsequence as claimed in one of claims 2 to
 4. 6. A host cell transfectedwith a vector as claimed in claim
 5. 7. A mono- or polyclonal antibodyobtained using a polypeptide as claimed in claim 1, and also thefragments, chimeric antibodies or immunoconjugates of said mono- orpolyclonal antibody.
 8. A composition useful for the diagnosis ofparaneoplastic neurological syndromes and/or for the early diagnosis ofthe formation of tumors, comprising a polypeptide or an epitopicfragment of said polypeptide as defined in claim
 1. 9. The use of apolypeptide as claimed in claim 1, for detecting the presence ofanti-CV2 antibodies in a biological sample.
 10. The use of mono- orpolyclonal antibodies or fragments, chimeric antibodies orimmunoconjugates thereof as claimed in claim 7, for purifying ordetecting a ULIP6 protein as claimed in claim 1, in a biological sample.11. A method for the diagnosis of paraneoplastic neurological syndromesand/or for the early diagnosis of the formation of cancerous tumors, inwhich autoantibodies directed against a ULIP 6 protein are demonstratedin a biological sample taken from an individual, by contacting abiological sample taken from an individual with a polypeptide as claimedin claim 1, optionally attached to a support, under conditions whichallow the formation of specific immunocomplexes between said polypeptideand the autoantibodies possibly present in the biological sample, anddetecting the specific immunocomplexes possibly formed.
 12. A kit forthe diagnosis of paraneoplastic neurological syndromes and for the earlydiagnosis of the formation of tumors, using a biological specimen,comprising: at least one ULIP6 polypeptide, as claimed in claim 1,optionally attached to a support, means for revealing the formation ofspecific antigen/antibody complexes between an anti-ULIP6 autoantibodyand said ULIP6 polypeptide, and/or means for quantifying thesecomplexes.
 13. A pharmaceutical composition comprising at least onetherapeutic agent chosen from a polypeptide as claimed in claim 1, anucleic acid as claimed in claims 2 to 4, or a nucleic acid comprisingan antisense sequence capable of hybridizing specifically with a nucleicacid as claimed in claims 2 to 4, or an antibody directed specificallyagainst the polypeptide as claimed in claim 7, in combination with apharmaceutically acceptable vehicle.
 14. The use of a therapeutic agentas defined in claim 13, for manufacturing a medicament intended to treatneurodegenerative diseases and neoplasms.